Wednesday, November 19, 2008

Easterly Flow


Today will be a partly sunny with no precipitation. Temps will get up into the lower 50s. Right now there is fairly high pressure over British Columbia and eastern Washington..with lower pressure offshore. This produces what we call an offshore pressure gradient....a change of pressure that accelerates winds to the west...particularly in gaps in the terrain (see pressure analysis this morning).
Take a look at the observed winds...the winds accelerate to the east in the Strait at Juan de Fuca...with reports of 50 mph winds at Seiku at the western exit. (see figure). Bellingham is getting modest northeasterlies gusting out of the Fraser River valley gap. And look in the Gorge...Troutdale (east of Portland) has moderate easterly flow. A computer simulation of the winds this morning shows these features and another easterly wind hot spot (eastern King County near Enumclaw and Black Diamond)--see figure. This is not a major easterly wind event...
A modest Pacific front will influence western Washington tomorrow...so expect rain to start around or just after breakfast. Another front later on Friday. Sunday still looks very nice...warmer and dry. So plan your outdoor activities (or raking leaves) then.

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